Process of preparing pentaerythritol tetracetate



' Patented my, 4, 1926.

preparing pentaerythritol tetracetate.

ITED STATES PATENT OFFICE.

ms '1. ennui, or

run, OI 1003381333,

income or In Drawing;

nocm'mn,

of -Preparin NEW YORK, ASSIGNOB TO EASTMAN KODAK COK- NEW YORK,

a CORPORATION 01 NEW You.

PBEPABING PENTAEBYTHBITOL TETBACETATE. I

Application fled August 1,

cmwem:

I, Hans T. CLARKE, a of Great Britain; reat Rochester, in the county of York, have invented Im rovements in ollowing is a full clear, and exact specification.

. object of the invention is This invention relates to processes of One to provide a relafor obtaining this substance. Another objectpf the invention is to provide a process in which acetic acid can be used directly instead of the relatively more expensive acetic anhydride.

pear. As .far as Other objects will hereinafter ap- I am aware, pentaerythritol tetracetate has been heretofore prepared by the action erythritol.

of acetic anhydride on penta- Since acetic anhydride is a relatively expensive ingredient, it is highly desirable to replace it with less expensive acetic acid. I have found that'this can be done be heated withacetic conditions that water if entaerythritol am under such formed during the esterification is removed during such reaction.

Preferably, I em.-' ploy an excess of glacial acetic acid, and the' water is fractionally. distilled away, practically as fast at it is essential, I also prefer action by the presence of such as sulfuric acid. Moreover, I

separate the products -of any excess reagents ti onal distillation,

formed. 'to facilitate the re-' While not a catalytic agent, refer to the reaction from or by-products by fraccontamination by sulfuric acid being desirably avoided by neutralizing the sulfuric acid,

tate, before the say with a metallic ace final distillations take place.

By way of illustration, a mixture of 250 parts of pentaerythritol,

cial acetic acid and 1 part of 1000 parts of glastrong or substantially anhydrous sulfuric acid is heated to approximatel' substantiall re which is a temperature be sible,-that is,

its boiling point, under ux conditions, the vapor owed to escape being kept at a low 105 C. as

throughout practically the long as pbs- Whole esterification reaction. This is not a critical temperature, but any temperature which facilitates the removal of water vapor Monentaerythritol readily separated from any i984. Serial 120. 729,498.

ors 'are rapidly I the exit from the water the temperature of the escaping vapor is allowed to rise to the boiling pomt of pure acetic acid. For instance, if the escaping vapor has been kept at or slightly below 105 0., the temperature is so adjusted that vapors atapproximately 118 C. can ass out,say into a final condenser. The essening or ending of the evolution of water vapor indicates a substantial completion of the esterification reaction, and any excess of acetic acid is then removed, while the temperature of the escaping vapors is kept around it boilin point. i

The pentaeryt ritol tetracetate boils at a practically constant temperature under reduced pressure,-for example, at about 184 to 186 C. under 9 mm. pressure or 190 to 192 C. under 20 mm. It is, therefore,

remaining ingredients of the reaction mlxt'ure by fractional distillation under such This fractional distillation leaves it in a substantiall pure state in which it issufficiently ee from impurities to be used in cellulosic solutions and dopes. be desired to keep it especially pure for special purposes, it may, of course, be dissolved in a solvent, such as hot benzene, from whichit is crystallized out upon cooling in the form of colorless needles.

In order to avoid contamination by V furic acid the latteris preferably k1lled? after the esterification and tional distillation of the product, by adding to' the reaction mixture an amountof metallic acetate (such .as anhydrous sodium acetate suffi ient to react with all of the sulfuric acid. This reaction forms-sodium sulfate and liberates acetic acid. The latter .distills off during the step described for its removal.

just sufiicient or slightly more than.

conditions.

before the frac- The sodium sulfate andany slight excess of sodium acetate remain behind, when the pentaerythritol tetracetate/ is distilled away thereby.

and condensed. p

It will be understood that the herein-- above recited details of proportions and temperaturesare purely illustrative and may be from the invention as defined in the claims. For example, an amount of acetic acid'can be used which is largely in excess of that required for the esterification reaction. But the process is operative when there is used altogether during the reaction only a stoichiometric or slightly greater amount of the acid. While I. refer to use acatalytic agent, such as ea furic acid, that may be omitted without rendering the action in operative. The exit temperatures of the vapor may also be varied within considerable limits, provided that free acetic acid always remalns in the reaction mixture and the evolution of the water. formed during the esterification is facilitated.

Having thus described my invention, What IcIaim' as new and desire to secure by Letters Patent is:

1. In the processof preparin thritol tetracetate, the steps 0 mixture of pentaerythritol. and to bring about the esterification, and, during the reaction, removing. the water formed pentaeryheating a 2. In the process of preparing entaerye thritol tetracetate, the. steps of boiing pentaerythritol with an excess of glacial acetic acid and removing the water formed dunng the esterification by fractional distillation.

3. In the process of preparing pentaerythritol tetracetate, the steps of heating pentaerythritol with an' excess of acetic acid and fractionally distilling off water formed during the esterification temperature of the escaping va ors below the boiling point-of acetic aci 4. In the process of preparing pentaerythritol tetracetate, the step taerythritol and acetic acid to promote the esterification and, during moving water formed therein by fractional distillation, the escaping vaporsbeing keptbelow 105 C.

5. In theprocess of preparing pent'a'erythritol tetracetate,.the steps of heating pentaerythritol and acetic acld to promote the esterification, and, during the reaction, fracdistillin'g ofi water formed therein tionally 7 until the evolution of water vapor substantially ceases.

greatly varied without departing .being converted into acetic acid amount of sulfuric acid unti takes place, durmg the reaction removing while keeping thes of heating penthe reaction, re- I of acetic acid and finally out the pentaerythritol Signed at Rochester, New York, this 25th v neaaees preparing pentaery promote the esterification, and

Mixture of .pentaerythritol, an excess of glacial acetate acid, and a relatively small amount of sulfuric acid, and, during the reaction, removing water formed therein from said mixtureby fractionaldistill'ation.

8. In the process of preparing pentaerythritol tetracetate,

the steps of heating a mixture of pentaerythritol tetracetate, .an

excess of glacial acetic acid, and a relatively small amount of sulfuric acid until esterification takes place, during the reaction removing by fractional distillation water [formed therein and thereafter distilling off the excess of acetic acid, the sulfuric acid mixture of pentaerythritol, an excess of 'gla-' cial acetic acid, and a regatively small esterification water formed therein by fractional distillation, the temperature of the esca pors being kept below the boiling point of acetic acid until evolution of'water vaporsubstantially ceases,

of acetic acid, reacting on the sulfuric acid. with sodium acetate after the evolution of water has ceased and before the distillationv distilling ofi the excess of all of the excess acetic acid, and finally distilling off the pentaerythritol tetracetate- 7 l0.- In the process of preparingpentaerythritoltetracetate, the steps of heating .a

mixture of pentaerythritol, and an excess 'of glacial acetic acid until esterification takes place, during the reaction removing water formed therein by fractional distillation, the temperature of the escaping vapors being kept below the boiling point of acetic acid until the evolution of water vaporsubstantiaflly'ceases, then distilling off the exseparating tetracetate.

day of July 1924.

. HANS T.

a metallic sulfateby 1 the addition of a metallic acetate to said 8B of preparing v pentaerypmg va- 

